Sulfur dispersion

Indocarbon sulfur, dispersed form Dystar Germany... 

Kayaku Homodye sulfur, dispersed form Nippon Kayaku Co., Ltd. Japan... 

Wang et al. [96] constructed a Na/S battery with a sodium metal anode, liquid electrolyte, and a sulfur (dispersed in polyacrylonitrile) composite cathode and tested its electrochemical characteristics at room temperature. The charge/discharge curves indicated that sodium could reversibly react with the composite cathode at room temperature. Average charge and discharge voltage was 1.8 and 1.4 V, respectively. Similar to lithium batteries, dendrite formation was noted as a critical problem for these cells. 

Dispersantfor Sulfur. The deposition of elemental sulfur in conduits through which a sulfur-containing gas is flowing can be reduced by providing a sulfur dispersant. The dispersant is an adduct of a primary alcohol and epichloro-hydrin, mixed with an aliphatic amine component [554]. 

The lower rejection ratio of 16 was accompanied by high selectivity in pyritic sulfur dispersion. This was due to the higher (10 mg/l) flocculant concentration which resulted in higher coal yield (93.1 wt) in the flocculated fraction. On the other extreme, when higher dispersant concentration (500 mg/l) was used with lower flocculant concentration (2 mg/l), much less coal was flocculated (77 wt) and more sulfur was apparently rejected (39 ). The intermediate conditions of 300 mg/l PAAX dispersant and 2 mg/l flocculant produced correspondingly intermediate results. 

Table I. Gradation of Materials Used in Sulfur Dispersion Study...

Sulfur Dispersion by Laboratory Mixer. The influence of the following variables on the dispersion of sulfur in asphalt was assessed in the laboratory. The mixes were prepared using 85-100 pen grade asphalt with all of the mix ingredients preheated to 140°-150°C. 

Attainment of fine sulfur dispersions such as described above are crucial to utilization of sulfur as an asphalt diluent. Provided that they remain stable, the binders will exhibit the sulfur-extended binder properties described previously. 

Increasing the proportion of sulfur in the binder, as shown by mixes No. 3, 4, 6, and 7 in Tables II and III, increases Marshall stability. This is attributed to the excess particulate sulfur, dispersed throughout the asphalt phase, which performs similar to a mineral filler. The particular sulfur may be observed using a microscope and is visible as small yellowish specks along broken mix surfaces. 

Sulfur dispersion in asphalt can be produced by various mechanical means. If the work is carried out over 120 °C, sulfur emulsions in asphalt can be obtained since sulfur liquifies at 117°C. 

Micrographic examination verifies that the addition of 10% sulfur to asphalt produces a monophasic product. The physical methods for determining these solubilities have been completed by chemical determinations of the sulfur content in each phase total sulfur dispersed and sulfur content of each part of the bituminous phase (maltenes, asphal-... 

Jong et prepared NR composites reinforced with hybrid filler consisting of defatted soy flour (DSF) and CB. Aqueous dispersions of DSF and CB were first mixed, and then blended with NR latex and sulfur dispersion, respectively. The homogenous composite mixtures were quickly freeze-dried and compression moulded to offer the NR composites. They found that the NR composites reinforced with 40% of hybrid filler (the ratio of DSF to CB was 1 1) exhibited a 90-fold improvement in the rubber plateau modulus compared with unfilled NR, showing a significant reinforcement effect by the hybrid filler. 

Rhenogran S Sulfur dispersed in EPDM/EVA, fast dispersing sulfur... 

Polyacrylates. To 200 g of the emulsion were added 1.1 g of a sulfur dispersion, 5 g of a zinc oxide dispersion, 2 g of a 50% water solution of zinc dibutyl dithiocarbamate, and 3.08 g of butylated bisphenol A dispersion. The mixture was vigorously stirred for 1 hr and films were cast on glass as above after the stirred-in air bubbles had disappeared. The films were dried and cured as above. The polymer was crosslinked by the usual vulcanization mechanism in which sulfur and zinc oxide form the crosslinks. Zinc dibutyl dithiocarbamate served as an accelerator, and the butylated bisphenol A was an antioxidant added to prevent degradation during cure. 

Poly styrene-butadiene). SBR-5362 To 143 g of emulsion were added 8.3 g of a zinc oxide dispersion, 3.7 g of a sulfur dispersion, 3.1 g of a butylated bisphenol A dispersion, and 2 g of a 50% by weight water solution of zinc dibutyl dithiocarbamate. The mixture was stirred, films cast, dried, and cured as above. The crosslinking mechanism again is the usual vulcanization. SBR-880 No additives were necessary since the material was self-crosslinking and is supplied with all necessary stabilizers. Films were cast, dried, and cured as above. 

Latex compound maturation is the period when the latex compound is stored after mixing, prior to use in the production line. After maturation the latex compound is mixed with a sulfur dispersion to crosslink the rubber molecules to improve their properties. The latex compounds are agitated for a maturation period of 1-7 days, depending on the nature of the production process and on the scale of the mixing operation. During maturation, crosslinking of the rubber molecules takes place inside discrete rubber particles dispersed in the aqueous phase of the latex and air bubbles introduced in the mixing rise to the surface. 

The equivalent quantities of sulfur dispersed are considerably greater than the amount needed to produce enough sulfate-based compound fertiliser to meet the whole UK requirement. 

Sulfur is difficult to disperse in NBR and particularly in soft compounds resulting in orange peal or dimpled surfaces or sulfur spots hence sulfur dispersions added at the beginning of the mixing cycle are recommended. It is even better, as shown in a 50 phr DIDP extended NBR in Table 2.31, to use sulfurless cures [20]. Some of the EV cure systems match the physical properties of the sulfur and semi-EV cures and exhibit improved scorch safety. 

---